Pudendal nerve block

Functional anatomy

origin: S2-4
exit pelvis via greater sciatic foramen
beneath piriformis
btwn sacrospinous & sacrotuberous ligaments
80% medial to pudendal a.
re-enter via lesser sciatic foramen
through Alcock's canal

medial to obturator internus muscle

divide into 3 branches

inferior rectal
- cutaneous branch
- motor supply to external anal sphincter
  - ± levator ani via "accessory rectal n."
perineal
- superficial branch
  - → posterior scrotal / labial n.
    - posterior aspect of scrotum / labia majora
- deep branch (motor)
  - muscle of pelvic floor & deep perineal pouch
  - external urethral sphincter
  - ± anterior part of external anal sphincter & levator ani
dorsal n. of penis / clitoris